Lightning rod with ionizing field



June 27, 1967 RlTTER 3,328,508

LIGHTNING ROD WI 'I H IONIZING FIELD FiledMarch 14, 1966 2 Sheets-Sheet 1 June 27, 1967 2 Sheets-Shem Filed March 14, 1966 FIG.2

United States Patent 3,328,508 LIGHTNING ROD WITH IONIZING FIELD Karlheinz Ritter, Vaduz, Liechtenstein, assignor to General Protection Establishment, Vaduz, Liechtenstein Filed Mar. 14, 1966, Ser. No. 533,950 Claims priority, application Switzerland, Mar. 16, 1965, 3,593/ 65 2 Claims. (Cl. 1744) ABSTRACT OF THE DISCLOSURE Lightning rods having around the rod at least one radioactive ionizing source consisting of americium-24 1, the ionizing power thereof being intensified by the provision of a magnetic field therearound so as to provide a volume of ionized air around the point of the rod which may conduct lightning bolts striking within the perimeter of ionizing air to the point of the lightning rod.

All radioactive lightning rods known up to now use radioactive sources comprising natural radioactive elements, principally radium.

Since the operating principle of the radioactive lightning rod uses the principal alpha ionising radiation which is corpuscular and difiicult to liberate one has always resorted to devices which cannot ensure the functioning to which they aspire, their source not being able to emit this radiation. In addition to the risks that this state of affairs imply, since protection from lightning is not assured these radioactive devices can give rise to health hazards owing to the emission of beta and especially gamma radiation from the radium.

The present invention has for object a radioactive lightning rod using new sources having high ionizing power, capable of liberating the alpha radiation of americium-241 a new isotope made available by the US. Atomic Energy Commission, and the efficiency of which is increased by an ionizing field. Thus, all these drawbacks of previous attempts are avoided and one can obtain an extremely certain yield, both from the aspect of lightning protection as from the health point of view, these new sources using americium-241 not being dangerous like those of radium.

The main feature of the invention resides then in the use of sources with the oxide of americium-241 held in a layer of noble metal, very resistant to abrasive and electro-chemical actions and furnishing an alpha emission of an energy and density higher to those of all ionizing sources known up to now. The half life of americium being around 480 years, these sources will keep their ionizing power in a practically linear manner for the life of the installations which must be protected.

The use of a magnetic field in this system of lightning protection, permits to amplify the ionizing power of the americium sources. This field makes its effects felt around the sources and the point as will appear hereinafter.

The radioactive sources are placed on a first electrode insulated from the stem and surrounding the same, near the point of the lightning rod. A second annular electrode, also insulated from the stem, brings an areodynamic protection to the sources and supports the upper end of a third electrode, helical in shape, but the lower extremity of which is electrically connected to the stem of the lightning rod, that is to say it has a ground potential.

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Other features and advantages of the invention will be more fully realised as the description thereof proceeds particularly when taken in connection with theappended drawing, wherein:

FIGURE 1 shows a lightning rod according to the invention, and

FIGURE 2 shows a variation thereof.

Referring to the drawings the lightning rod shown in FIGURE 1 comprises a stem 1 suitably grounded, an insulator 3 bearing an electrode 4 on the periphery of which are placed the radioactive ionising sources 5, a second annular insulator 6 secured below the first on stem 1 and bearing electrode 7 by means of spokes 8 and hub 9.

This assembly is completed by a helical electrode 10 surrounding stem 1 at the level of insulators 3 and 6 and connected by its upper end to electrode 7 and by its lower end to a metallic ring 11 secured directly to the stem by suitable means such as welding.

The ionizing sources with americium oxide have for function, to anticipate and especially, to amplify the ionizing phenomena to which will give rise the present system of radioactive lightning rod with magnetic field.

At the approach of atmospheric discharges, the gradient assumes very high values, of several thousands, and even tens of thousands, of volts by meters of height (A. Brash and F. Lange, Zeitf. Phys. 70, 10 (1931), have measured gradients going up to 100,000 volts/m.). The lightning rod subject of the present invention having to be installed at a minimum height of 15 meters above the ground and being in fact placed in most cases much higher, will always be immersed upon the approach of discharges, in electrostatic gradients of at least 100,000 volts, and even more easily, of 500,000 to 1,000,000 volts or more. In parallel fashion, this hyperbolic increase of gradient will determine:

(1) A current in the helical electrode, the anode of which is branched on a crown strongly insulated from the stem, assuming the values of the gradients surrounding the system, that is to say, tens of thousands, or even hundreds of thousands of volts and the cathode of which is connected to the ground, that is to say it has zero potential. There will therefore be a strong field action;

(2) The metallic ionizing sources with americium-241 will bear the same electrostatic voltages owing to the gradient in which the device is immersed since they are placed on a crown strongly insulated from the stem. As a consequence, the alpha emission will be strongly accelerated, and at a given moment, will give rise to the phenomena of shock ionization. The triggering of this phenomena will be anticipated and intensified by the field action.

The present invention thus provides a system for strongly ionizing a volume of air, the intensity of which decreases towards the perimeter of the zone to be protected. If lightning approaches this perimeter, it will be captured, and, following the path of least resistance, will be directed toward its center and the shock point which will lead it to the ground.

The electrodes used in the present invention can be composed of any metallic material well known for use in this fiield. The insulators are also of known construciions.

What is claimed is:

1. Radioactive lightning arresting device comprising a grounded rod, an electrode insulatingly secured to said rod having on the periphery thereof at least one metallic radioactive ionizing source consisting of americium-241 contained in a capsule of material able to permit alpha rays emanating from said americinm-241 to emerge freely into the ambient atmosphere to cause shock ionization of the air; and electrode means for producing a magnetic field around said radioactive ionizing source for anticipating and intensifying said shock ionization whereby air surrounding said device becomes strongly ionized along a given perimeter in which all lightning which may strike will be capturedand following the path of least resistance constituted by the ionized air in said perimeter will be led to said grounded rod and hence to the ground.

2. Radioactive lightning arresting device according to claim 1, wherein said electrode means for producing a 4, i magnetic field consists of an electrode helically disposed around said rod and source and having one extremity at ground potential and another extremity at atmospheric gradient.

References Cited UNITED STATES PATENTS 2,644,026 6/ 1953 Grenier et a1 174-4 2,854,499 9/1958 Capart 1744 FOREIGN PATENTS 610,061 10/ 1960 Italy.

LARAMIE E. ASKIN, Primary Examiner. 

1. RADIOACTIVE LIGHTNING ARRESTING DEVICE COMPRISING A GROUNDED ROD, AN ELECTRODE INSULATINGLY SECURED TO SAID ROD HAVING ON THE PERIPHERY THEREOF AT LEAST ONE METALLIC RADIOACTIVE IONIZING SOURCE CONSISTING OF AMERICIUM-241 CONTAINED IN A CAPSULE OF MATERIAL ABLE TO PERMIT ALPHA RAYS EMANATING FROM SAID AMERICIUM-241 TO EMERGE FREELY INTO THE AMBIENT ATMOSPHERE TO CAUSE SHOCK IONIZATION OF THE AIR; AND ELECTRODE MEANS FOR PRODUCING A MAGNETIC FIELD AROUND SAID RADIOACTIVE IONIZING SOURCE FOR ANTICIPATING AND INTENSIFYING SAID SHOCK IONIZATION WHEREBY AIR SURROUNDING SAID DEVICE BECOMES STRONGLY IONIZED ALONG A GIVEN PERIMETER IN WHICH ALL LIGHTNING WHICH MAY STRIKE WILL BE CAPTURED AND FOLLOWING THE PATH OF LEAST RESISTANCE CONSTITUTED BY THE IONIZED AIR IN SAID PERIMETER WILL BE LED TO SAID GROUNDED ROD AND HENCE TO THE GROUND. 